modified 2119-ish to normal sentence

index.html

@@ -5969,7 +5969,7 @@ <h4 id="elements_of_block_heading">
 <span its-locale-filter-list="en" lang="en">Elements of Block Heading</span>
 <span its-locale-filter-list="ja" lang="ja">別行見出しの構成</span>
 </h4>
-      <p its-locale-filter-list="en" lang="en">JIS X 4051 describes the elements of a <a href="#term.block-heading" class="termref">block heading</a> as three levels: <a href="#term.top-level-heading" class="termref">top level heading</a>, medium level heading, and low level heading. These block headings SHALL have a heading title, and MAY have a <a href="#term.label-name" class="termref">label name</a>, number, and heading <a href="#term.subtitle" class="termref">subtitle</a> (see [[[#fig3_1_6]]]).</p>
+      <p its-locale-filter-list="en" lang="en">JIS X 4051 describes the elements of a <a href="#term.block-heading" class="termref">block heading</a> as three levels: <a href="#term.top-level-heading" class="termref">top level heading</a>, medium level heading, and low level heading. These block headings have to have a heading title, and may have a <a href="#term.label-name" class="termref">label name</a>, number, and heading <a href="#term.subtitle" class="termref">subtitle</a> (see [[[#fig3_1_6]]]).</p>
       <p its-locale-filter-list="ja" lang="ja">別行見出しの構成については，JIS X 4051では大見出し，中見出し及び小見出しを定義し，それぞれ<span class="index" id="d8e584">ラベル名</span>，<span class="index" id="d8e587">番号</span>，<span class="index" id="d8e590">見出し文字列</span>及び<span class="index" id="d8e593">副題</span>で構成するとしている（[[[#fig3_1_6]]]）．ただし，ラベル名，番号及び副題は，必須要素ではなく，省略してもよいとなっている．</p>
       <figure id="fig3_1_6"> 
       <img its-locale-filter-list="en" src="images/img3_1_6.png" alt="Elements of block heading" width="403" height="251">